This application relates to and claims priority to corresponding Germany Patent Application No. 100 39 712.3, which was filed on Aug. 14, 2000, and which is incorporated by reference herein.
The invention relates to an optical element mount comprising an optical element holding frame and a mount stack.
U.S. Pat. No. 5,822,133 discloses a optical element mount which displaces two carrier elements for lenses axially in relation to one another along an optical axis, for improving the imaging quality in an optical lens. For this purpose, the above mentioned document uses a plurality of hydraulic actuators which can be moved predominantly via a fluid. The document describes arrangements in which it is possible to achieve small manipulations in the axial direction, the so called xe2x80x9cZ-directionxe2x80x9d, via actuators arranged symmetrically in relation to the optical axis. For this purpose, individual configurations of the invention provide three mechanisms which are distributed symmetrically about the optical axis of the respective lenses, and each comprise an actuator which can be actuated hydraulically or piezzoelectrically, and corresponding lever arrangements which may be produced from monolithically in the form of flexure hinges. This construction makes it possible to realize a Z-manipulation of the lens.
The use of three actuators requires a very high level of regulating outlay. Moreover, integrating the actuators between the two components results in the disadvantage that the overall structural unit is relatively large and, in particular in order to leave free sufficiently large central openings for the corresponding lenses, requires a very large amount of space in the axial direction and in the radial direction. As a result, it is also the case that the design will only have a low level of rigidity.
It is also known, in particular from the field of photography, to realize the axial displacement of lenses or other optical elements in relation to one another in that at least one of the carrier elements for one of the optical lenses or the like is placed in a threaded element, and it is thus possible to vary the spacings between the individual components via rotation of the individual components in relation to one another.
On account of the friction during such an adjustment of the spacing between two components in relation to one another, and a possibly occurring slip/stick effect, this type of manipulation can only be used when there is no need for any high levels of accuracy. The use of high-performance lenses, for example in the field of microlithography, is thus ruled out.
The object of the invention is to provide a optical element mount for an optical element mount comprising an optical element holding frame and a mount stack allowing with a very compact and space-saving construction, very precise adjustment of the position of the two components in relation to one another and being of very rigid configuration.
This object is achieved according to the invention by the features specified in claim 1.
Since each of the components has the at least three hinges which are connected to respectively corresponding hinges of the respectively other component via a lever element, it is possible to realize a very compact construction. Moreover, in this case, only at least six hinges and at least three lever elements are necessary in order to connect the two components in the axial direction. With an appropriate selection of the hinges, in this case it is possible to utilize, for example, very rigid solid-body hinges, this construction may be realized, on the one hand, in a very space-saving manner in the axial direction and, on the other hand, in very rigid form.
The lever elements of the pairs of hinges are connected to at least one adjacent lever of at least one of the adjacent pairs of hinges via at least one lever and at least one further hinge in each case. By virtue of this connection, the individual pairs of hinges correspond directly to one another.
For example with four pairs of hinges and the same lengths for the lever elements and the levers, as is the case, for example, with the pairs of hinges arranged in the manner of a square, in which case the further hinges are then displaced some way inward in each case in relation to the theoretical side edges of the square, it is possible to realize a very uniform movement. The optical element mount may then be activated via the at least two levers, which may be connected to one another in turn and thus provide the possibility of it being possible for the optical element mount, in a very favorable configuration, to be operated by a single actuator.
In this case, depending on the amount of space present, it is possible for the levers to project radially to the corresponding extent beyond the structural unit, with the result that, by virtue of the very long levers, even if only a comparatively small amount of force is available, very rigid configuration of the hinges, which may be realized for example as flexure hinges, is possible since the forces acting on the lever elements are correspondingly reinforced by the length of the levers. The small angle of rotation of the individual levers and lever elements thus results in very good linearity of the desired movement in conjunction with a very small lateral movement of the components, said movement being caused by the lever elements of the individual pairs of hinges.
This results in the very compact and straightforward construction which, on account of the very long levers and of the associated possibility of the corresponding hinges being of very rigid configuration, permits a very rigid configuration of the optical element mount as a whole. This, in turn, results in very advantageous properties on account of the consequently very high eigenfrequency of the optical element mount.